1. Field of the Invention
The present invention relates to a Braille reading display terminal device which has an improved interface between the unit and its host computer.
2. Description of the Related Art
A conventional Braille reading display device is connected to a personal computer serving as a host computer and has an intelligence function of inputting Braille information, reading the information from a tactile pins display, and outputting the information as a voice in combination with a voice synthesizer.
The conventional Braille reading display device comprises a microprocessor having a ROM for storing Braille codes and a RAM for temporarily storing processing information to input/output Braille information, and a DIP SW (dual inline package switch) for selecting various Braille notations (e.g., six-dot pattern and eight-dot pattern) from the ROM.
Like generally-used peripheral terminal units of personal computers, the conventional Braille reading display device is connected to various personal computers through RS-232C or CENTRONICS, both of which are standard interfaces, with the result that information is transferred in series o in parallel between the device and the personal computers through the interface. Information processing peculiar to the Braille reading display device is executed by the microprocessor included therein.
However, the conventional braille reading display device has the following drawbacks.
(1) Since a widespread Braille notation method has not yet been established, information stored in a ROM has to be rewritten and the ROM has to be exchanged with another in accordance with various Braille notation methods. Since an exchange of ROMs is difficult for users, it is usually performed by makers. In most cases, however, it is difficult even for makers because the ROMs are widely used.
(2) It is troublesome to select one of interfaces RS-232C and CENTRONICS and set a transfer speed, various parameters, etc. using the DIP SW, in order to select a necessary one from various Braille notations stored in a ROM.
(3) Since a program of grammar (e.g., Six-Dot Japanese Braille Notation) proper to Braille notations has to be stored in a ROM, the capacity of the ROM is increased.
(4) Since there are different, methods for representing, Chinese characters by Braille notations, the Braille reading display device cannot be applied to all the methods.
(5) Since various peripheral units are required in addition to a CPU, a ROM, and a RAM, the cost of hardware is increased.
As described above, the conventional Braille display device has the drawback of increased total costs including running costs, debug costs, and the like, which puts much strain on both makers and users.